Our long-range goal is to develop systematic procedures for the identification of DNA damage occurring at the level of a few parts per million. We are emphasizing the determination of the structures of compounds produced in the reaction of cross-linking agents with DNA. A principal objective in the coming year will be the reaction of diepoxybutane with nucleosides and DNA. The simpler model compound, ethylene oxide, will also be investigated. Structure determination of products, at the microgram level, will be accomplished using ultraviolet, pKa, nuclear magnetic resonance and mass spectrometric information, and chemical transformation. A catalog of ultraviolet and pKa data for bases, nucleosides, and their mono- and dialkyl derivatives is being assembled. We hope to produce a set of tables, and a rule-book, which will be made generaly available. It should be possible to plug in wavelength and dissociation data directly, and obtain maximal structural information by a simple procedure. The reactions of arcolein, a possible DNA cross-linking agent, with nucleosides will be investigated, and the products identified. In the course of the above studies, we will attempt to devise new microchemical tests, and spectroscopic procedures for the identification of reaction products of DNA with external reagents.